WASHINGTON -- The new era of Nationals pitching is set to begin Monday night. Right-hander Josiah Gray, one of the headliners in the Max Scherzer and Trea Turner megadeal with the Dodgers, is slated to start against the Phillies at 7:05 p.m. ET at Nationals Park.

The 23-year-old arrived in Washington on Saturday and was on the field on Sunday morning meeting his new teammates and coaches.

“It’s awesome,” manager Dave Martinez said. “[I’m] excited to watch him pitch. … He’s excited to be here. We’re excited to have him.”

Gray is ranked as the Nationals’ No. 2 prospect and the No. 41 overall prospect, per MLB Pipeline. He made his Major League debut on July 20, and he comes to the Nats with two appearances, including his first big league start on July 25. Gray pitched eight innings for the Dodgers, posting a 6.75 ERA and allowing six runs on seven hits, five walks and four home runs while striking out 13. Prior to his callup, he recorded a 2.87 ERA and issued only two walks over 15 2/3 innings in Triple-A.

Martinez lauded Gray for having a “very live fastball,” which averages 94-95 mph, and he also noted his breaking ball and changeup. MLB Pipeline graded Gray’s pitch mix (on a scale of 20-80) as 60 fastball, 55 slider, 50 curveball and 50 changeup.

“Everything I’ve heard about him, he’s a great, great kid,” Martinez said. “He puts the work in and he’s very competitive. I’m looking forward to building a relationship with him and moving forward watching him compete.”

The Nationals do not plan to implement any pitch count or innings limitation on Gray in his debut. After watching him on videos, Martinez and the coaching staff will be able to evaluate his in-game adjustments live.

“Like I told him today, ‘I’m here to listen to you more than you listen to me,’” Martinez said. “‘I want you to tell me what you feel, what’s going on -- and we’ll have these conversations throughout the days here, not just when you pitch but the day after, whenever. But we’re going to keep an eye on you, we’re excited that you’re here, we know that you’re going to be able to help us, so just go out there and have fun.’”

In a corresponding roster move, the Nats optioned right-handed reliever Tanner Rainey to Triple-A Rochester to work on his mechanics and throwing strikes while pitching every other day.

Gray is the second player acquired at the Trade Deadline to join the Nationals’ big league roster. Right-hander Mason Thompson, their No. 16 prospect who was acquired in the Daniel Hudson deal with the Padres, was recalled to the active roster on Saturday. Martinez said the other new prospects will begin their time with the Nationals at the same levels from their previous organization. That includes the Nats’ No. 1 prospect, catcher Keibert Ruiz, who is playing in Triple-A.